  
public class DuckSimulator
{
	public static void main(String[] args)
	{
		DuckSimulator simulator = new DuckSimulator();
		simulator.simulate();
	}
	
	void simulate()
	{
		Quackable mallardDuck = new MallardDuck();
		Quackable redheadDuck = new RedheadDuck();
		Quackable duckCall = new DuckCall();
		Quackable rubberDuck = new RubberDuck();
		
		System.out.println("\nDuck Simulator");
		
		simulate(mallardDuck);
		simulate(redheadDuck);
		simulate(duckCall);
		simulate(rubberDuck);
	}
	
	void	simulate(Quackable duck)
	{
		duck.quack();
	}
	
}
